1. The Field of the Invention
The present invention relates to over pressurization valves to prevent over pressurization of a pressure infusion bag. In particular, the present invention relates to an over pressurization valve allowing a user to manually select from at least a first and second over pressurization limit.
2. The Relevant Technology
Infusion devices are used for the subcutaneous administration, to humans or animals, of intravenous fluids such as blood, nutrients, medicine or saline. The fluids are stored and administered from pliant infusate bags typically made from plastic film materials. The infusate bags facilitate the administration of infusate fluids, while limiting the amount of air that is transferred to the patient with the fluid.
Infusion devices allow fluids to be administered to patients in a variety of manners. A common administration technique involves suspending an infusate bag from a hook or peg and allowing gravity to provide the force needed to deliver the fluid to the patient by the means of a delivery line. Where suspension administration is utilized, the infusate bag includes an outlet tube at the lower end of the bag. A delivery tube is attached to the outlet tube for delivering the fluid from the bag to the patient. The delivery tube usually includes an observable drop-feed device and an adjustable flow delivery valve for allowing medical staff to regulate the fluid flow rate.
There are limitations to using suspension to administer IV fluids. Where gravitational forces are the sole means of administering fluid, the viscosity of some fluids such as blood and plasma, makes delivery of the fluids problematic. The problem is exacerbated where the fluid must be delivered quickly and efficiently, as with major traumas where large amounts of blood are required in a short amount of time. To facilitate a higher rate of infusate delivery, such as is required with high viscosity fluids, medical staff utilize various methods to increase the pressure on the infusate fluid. Examples of such methods include, pressure pumps, inflation cuffs, inflation bladders, or even manual compression of the infusate bag. Pressure pumps, inflation cuffs, inflation bladders, and manual compression of the infusate bags also allow fluids to be delivered to the patient as needed during ambulation of the patient.
Among the methods of providing compression of the infusate bag, pressure infusion bags have been accepted in the medical products industry as an effective and inexpensive method for providing the pressure required by highly viscous fluids, ambulation, and many other circumstances. Pressure infusion bags comprise an inflatable air bladder with a sleeve or pouch for holding the infusate bag. When the user inflates the air bladder, pressure is exherted on the infusate bag contained in the sleeve, thus providing the pressure needed to deliver the fluid.
An over pressurization valve is often utilized in connection with the pressure infusion bag to prevent additional pressurization of the pressure infusion bag once a desired pressurization has been reached. Typically, the over pressurization valve is configured to prevent rupturing of the pressure infusion bag. However, the over pressurization limit can also correspond with a desired rate of infusate delivery.
One problem associated with over pressurization valves is that a single over pressurization limit is provided by the over pressurization valves. Different over pressurization limits may be desired for different types of infusate, in different types of clinical settings, and/or for different types of procedures. For example, an over pressurization limit recommended to provide a desired delivery rate for medications can be different from the over pressurization limit needed to accommodate the desired delivery rate for blood or plasma. Additionally, the over pressurization limit for providing a desired delivery rate for blood for routine procedures may be insufficient to provide the delivery rate desired in trauma and major surgical settings.